Biomedical subjects

B Nicolaus

Publications and source records attributed to B Nicolaus.

26 records · Page 2Linked to original sources

PubMed1993

The glycolipid of Halobacterium trapanicum.

The structural elucidation of the polar lipids in Halobacterium trapanicum is reported with particular emphasis on a new sulfated disaccharide derivative of 2,3-di-O-phytanyl-sn-glycerol. The full structural designation of this glycolipid is 2,3-di-O-phytanyl-1-O- (mannopyranosyl-(2-sulfate)-alpha-D-1-2-glucopyranosyl-alpha-D)-sn-glyce rol. The value of glycolipid structures in the taxonomy of halophilic Archaea is also discussed.

Carbohydrate Sequence↗

PubMed1992

Glycolipids from Thermotoga maritima, a hyperthermophilic microorganism belonging to Bacteria domain.

Two novel glycolipids with a very rare alpha(1-->4) diglucosyl structure have been isolated from the thermophilic bacterium Thermotoga maritima. The structures of these compounds, on the basis of chemical procedures and spectroscopic studies (FAB-MS and NMR), were shown to be: 1(3),2-dipalmitoyl-3(1)-[glucopyranosyl-(6-decanoyl)-alpha-D-(1-->4)- glucopyranosyl-alpha-D]-glycerol (Glycolipid 1) and 1(3),2-dipalmitoyl-3(1)-[glucopyranosyl-alpha-D-(1-->4)-glucopyranosyl- alpha-D]-glycerol (Glycolipid 2).

Chromatography, Gas↗

PubMed1990

Determination of hydride transfer stereospecificity of NADH-dependent alcohol-aldehyde/ketone oxidoreductase from Sulfolobus solfataricus.

This paper describes the determination of stereospecificity of hydride transfer reaction of an alcohol dehydrogenase isolated from the archaebacterium Sulfolobus solfataricus. The 1H-NMR and EI-MS data indicate that the enzyme transfers the pro-R hydrogen from coenzyme to substrate and is therefore an A-specific dehydrogenase.

Alcohol Dehydrogenase↗

PubMed1990

Calditol tetraether lipids of the archaebacterium Sulfolobus solfataricus. Biosynthetic studies.

Lipids from the archaebacterium Sulfolobus solfataricus are based on 72-membered macrocyclic tetraethers made up from two C40 diol units differently cyclized and either two glycerol moieties or one glycerol moiety and a unique branched-chain nonitol named calditol (glycerodialkylnonitol tetraethers, GDNTs). To elucidate the biosynthesis of calditol and related tetraethers, labelled precursors, [U-14C,1(3)-3H]glycerol, [U-14C,2-3H]glycerol, D-[1-14C,6-3H]glucose, D-[6-14C,1-3H]glucose, D-[1-14C,2-3H]glucose, D-[1-14C,6-3H]fructose and D-[1-14C]galactose, were fed to S. solfataricus. Without regard to stereochemistry or phosphorylation, incorporation experiments provided evidence that the biosynthesis of calditol occurs via an aldolic condensation between dihydroxyacetone and fructose, through a 2-oxo derivative of calditol as an intermediate. The latter is in turn reduced and then alkylated to yield the GDNTs. The biogenetic origins of both glycerol and C40 isoprenoid moieties of GDNTs are also discussed.

Acetylation↗

PubMed1988

A simple chromatographic procedure for the detection of cyclized archaebacterial glycerol-bisdiphytanyl-glycerol tetraether core lipids.

Archaebacterial glycerol-bisdiphytanyl-glycerol tetraether core lipids containing from one to eight cyclopentane rings could be resolved from each other and from the parent uncyclized C40, C40 lipid by TLC. The core lipids of examples from the genera Methanobacterium, Methanobrevibacter, Methanogenium and Methanoplanus did not contain cyclized forms of glycerol-bisdiphytanyl-glycerol tetraethers, whereas the core lipids of Methanosarcina barkeri contained glycerol-bisdiphytanyl-glycerol tetraethers with from one to three cyclopentane rings in each C40 isopranoid chain.

Archaea↗

PubMed1985

Insensitivity of archaebacterial ribosomes to protein synthesis inhibitors. Evolutionary implications.

The effect on Sulfolobus solfataricus (an extremely thermoacidophilic archaebacterium) of selected inhibitors affecting reactions of the polypeptide elongation cycle has been tested by using poly(U) and poly(UG) directed cell-free systems. The results reveal a unique pattern of antibiotic sensitivity of Sulfolobus ribosomes with an inhibitory effect observed for only three of 60 compounds tested. Through comparison with suitable eubacterial and eukaryotic cell-free systems the insensitivity of Sulfolobus ribosomes to most inhibitors of protein synthesis appears to reflect a phylogenetic distinction of ribosome structure, rather than the high temperature conditions of the Sulfolobus assay system. In this respect ribosomes of thermoacidophilic archaebacteria differ not only from their eubacterial and eukaryotic counterparts, but also from ribosomes of archaebacteria belonging to the methanogenic-halophilic branch of the 'third' kingdom. The evolutionary implications of these findings are discussed.

Anti-Bacterial Agents↗

PubMed1984

Glucose metabolism in the extreme thermoacidophilic archaebacterium Sulfolobus solfataricus.

Sulfolobus solfataricus is a thermophilic archaebacterium able to grow at 87 degrees C and pH 3.5 on glucose as sole carbon source. The organism metabolizes glucose by two main routes. The first route involves an ATP-dependent phosphorylation to give glucose 6-phosphate, which readily isomerizes to fructose 6-phosphate. In the second route, glucose is converted into gluconate by an NAD+-dependent dehydrogenation; gluconate is then dehydrated to 2-keto-3-deoxygluconate, which, in turn, is cleaved to pyruvate and glyceraldehyde. Each metabolic step has been tested in vitro at 70 degrees C on dialysed homogenates or partially purified fractions; minimal requirements of single enzymes have been evaluated. Identification of the intermediates is based on chromatographic, spectroscopic and/or synthetic evidence and on specific enzymic assays. The oxidative breakdown of glucose to pyruvate occurring in S. solfataricus differs from the Entner-Doudoroff pattern in that there is an absence of any phosphorylation step.

Adenosine Triphosphate↗

PubMed1982

Archaebacterial elongation factor Tu insensitive to pulvomycin and kirromycin.

A spermine-dependent, polyphenylalanine-synthesizing cell-free system having an optimum activity at 75-85 degrees C, has been developed from the extremely thermoacidophilic archaebacterium Caldariella acidophila. The C. acidophila system is totally insensitive to the EF-Tu targeted antibiotics pulvomycin (at 40 degrees C) and kirromycin (at 47-72 degrees C) contrary to control systems derived from both mesophilic (Escherichia coli) and thermoacidophilic (Bacillus acidocaldarius) eubacteria. The archaebacterial EF-Tu-equivalent factor is also immunologically unrelated to eubacterial EF-Tu and does not cross react with antibodies against Escherichia coli EF-Tu. The pulvomycin and kirromycin reactions thus provide new phyletic markers for archaebacterial ancestry.

Aminoglycosides↗